1. Field of the Invention
The invention relates to a transport device in the form of a long stator linear motor, comprising at least one transport unit and a transport track composed of a plurality of transport segments arranged consecutively in the longitudinal direction, having a starting point and an ending point, along which the transport unit can be moved in the longitudinal direction along a movement path predefined by the transport segments, wherein the transport track comprises at least one curved transport segment having a curved movement path that is located in a two-dimensional plane, wherein the two-dimensional plane defines a plane of movement in which the transport unit can be moved along the entire transport track.
2. Discussion of Background Information
Essentially all modern production equipment makes it necessary to move parts or components between individual handling or production stations by way of transport devices, including over extended transport distances. A multitude of transport or conveying devices are known for this purpose. Frequently, continuous-flow conveyors in various designs are used for this purpose. Conventional continuous-flow conveyors are conveyor belts in various embodiments in which a rotational movement of an electric drive is converted into a linear movement of the conveyor belt. Such conventional continuous-flow conveyors significantly limit flexibility, and in particular it is not possible to individually transport single transport units. To remedy this situation and meet the requirements of modern, flexible transport devices, what are known as long stator linear motors (LLM) are being used to an increased extent, displacing conventional continuous-flow conveyors.
In the case of a long stator linear motor, a plurality of electric drive coils forming the stator are arranged next to one another along a transport track in a stationary manner. A number of drive magnets, either in the form of permanent magnets or an electric coil or a squirrel cage winding, are arranged on a transport unit and cooperate with the drive coils. The (electro)magnetic fields of the drive magnets and the drive coils cooperate so as to generate a propulsive force for the transport unit, which moves the transport unit forward. The long stator linear motor can be implemented as a synchronous machine, either in self-excited or separately excited form, or as an asynchronous machine. By activating the individual drive coils for controlling the magnetic flux, the magnitude of the propulsive force is influenced, and the transport unit can be moved along the transport track in the desired manner. It is also possible to arrange a plurality of transport units along the transport track, in which the movements can be controlled individually and separately from one another by energizing the respective drive coils cooperating with a transport unit, in general by applying a voltage.
A long stator linear motor is characterized, in particular, by a better and more flexible utilization across the entire operating range of the movement (position, velocity, acceleration), individual closed-loop/open-loop control of the transport units along the transport track, improved energy utilization, reduced maintenance costs due to the lower number of wear components, easy replacement of the transport units, efficient monitoring and fault detection, and an optimized product flow along the transport track. Examples of such long stator linear motors can be derived from WO 2013/143783 A1, U.S. Pat. No. 6,876,107 B2, US 2013/0074724 A1 or WO 2004/103792 A1.
Frequently, the long stator or a transport track is also composed in the form of individual track sections, which in turn are made of joined transport segments. This modularity allows a long stator linear motor to have a simpler design, in particular when defined track sections and transport segments are used. The design configuration of the long stator linear motor, which is to say, for example, the design of the drive coils, the conveyor track, the transport units, the guides of the transport unit, and so forth, can differ, of course, however the fundamental functional principle of a long stator linear motor always remains the same.
In general, such transport devices in the form of a long stator linear motor are usually arranged in one plane, so that the transport units are moved along a planar transport track. The transport track can be composed of transport segments in the form of curve segments, straight segments or switches; the movement, however, always takes place in the same plane. For certain applications, however, it may be necessary to move transport units from one plane into another plane, for example to transport components from a lower to a higher plane.
WO 2014/047104 A1, for example, proposes a transport device in the form of a long stator linear motor which can comprise 180° curved segments or angled transport segments to overcome vertical differences in height. A transport unit is essentially moved from a first horizontal plane into a higher or lower second horizontal plane, wherein the two planes are arranged parallel to one another. It is not possible, however, to transfer the transport unit into a vertical plane, for example.
WO 2015/042409 A1 likewise discloses a transport device in the form of a long stator linear motor (LLM), which makes it possible to move a transport unit, for example, from a horizontal plane into a vertical plane, changing the orientation of the transport unit from horizontal to vertical. For this purpose, various vertical and horizontal transport segments are provided. However, it is disadvantageous that a large number of different transport segments is required to change from the horizontal plane to the vertical plane, and that the flexibility with respect to the number and position of the movement planes is limited. Moreover, the design of the transport segments required for changing the movement plane is very complex.
EP 3 031 756 B1 discloses a transport system in the form of a long stator linear motor comprising stationary transport tracks, on which transport units can be moved in the known manner according to the motor principle. Furthermore, a conveying device, on which a connecting track section can be moved, is arranged at the ends of the stationary transport tracks in the transverse direction. The connecting track section can be moved on the conveying device so as to be brought into alignment with the stationary transport tracks. In this way, a transport unit can be moved from a stationary transport track onto the connecting track section, moved on the conveying device to another stationary transport track by way of the connecting track section, and continue to be moved along this other stationary transport track. Additionally, the conveying device can be moved vertically, whereby multiple stationary transport tracks arranged vertically on top of one another can be achieved. In addition to the very complex design, however, it is a disadvantage that no continuous movement of a transport unit between the stationary transport tracks is possible, and that only a movement in superimposed parallel planes is possible.
EP 1 123 884 A1 discloses a device for diverting containers from a movement track. The device comprises a movement track having multiple transport segments in the form of a long stator linear motor, along which rigid pushers can be moved in the longitudinal direction. The diversion is carried out in a direction transversely to the direction of movement by moving the pushers along a diversion section having a certain contour. Wheels including entrainment elements are provided at the end and at the beginning of the LLM movement track, and a return section is provided beneath the movement track. The pushers can be transported on the return section, or from there back to the movement track, by way of the wheels. Since the wheels directly adjoin the movement track, it is not possible to move the pushers smoothly, which would be disadvantageous, in particular, for the transport of sensitive objects.